ACT Math · Statistics and data analysis
Data set A has a standard deviation of 4. Data set B has a standard deviation of 9. Both sets have the same mean. Which set has values…
Data set A has a standard deviation of 4. Data set B has a standard deviation of 9. Both sets have the same mean. Which set has values that are more spread out from the mean?
Answer and explanation
Answer: J: Set B
The standard deviation measures how far values typically are from the mean. When two data sets have the same mean, the one with the larger standard deviation is more spread out. Set B has a standard deviation of , which is larger than , so Set B is more spread out, choice J. Choice F reverses the comparison. Choice H (equally spread out) is wrong because the standard deviations differ. Choice G (cannot be determined) is wrong because the question gives exactly the information needed: the same mean and two standard deviations.
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